1 /* 2 * Copyright (c) 1996 John S. Dyson 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice immediately at the beginning of the file, without modification, 10 * this list of conditions, and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 3. Absolutely no warranty of function or purpose is made by the author 15 * John S. Dyson. 16 * 4. Modifications may be freely made to this file if the above conditions 17 * are met. 18 * 19 * $FreeBSD: src/sys/kern/sys_pipe.c,v 1.60.2.13 2002/08/05 15:05:15 des Exp $ 20 * $DragonFly: src/sys/kern/sys_pipe.c,v 1.6 2003/07/26 18:12:44 dillon Exp $ 21 */ 22 23 /* 24 * This file contains a high-performance replacement for the socket-based 25 * pipes scheme originally used in FreeBSD/4.4Lite. It does not support 26 * all features of sockets, but does do everything that pipes normally 27 * do. 28 */ 29 30 /* 31 * This code has two modes of operation, a small write mode and a large 32 * write mode. The small write mode acts like conventional pipes with 33 * a kernel buffer. If the buffer is less than PIPE_MINDIRECT, then the 34 * "normal" pipe buffering is done. If the buffer is between PIPE_MINDIRECT 35 * and PIPE_SIZE in size, it is fully mapped and wired into the kernel, and 36 * the receiving process can copy it directly from the pages in the sending 37 * process. 38 * 39 * If the sending process receives a signal, it is possible that it will 40 * go away, and certainly its address space can change, because control 41 * is returned back to the user-mode side. In that case, the pipe code 42 * arranges to copy the buffer supplied by the user process, to a pageable 43 * kernel buffer, and the receiving process will grab the data from the 44 * pageable kernel buffer. Since signals don't happen all that often, 45 * the copy operation is normally eliminated. 46 * 47 * The constant PIPE_MINDIRECT is chosen to make sure that buffering will 48 * happen for small transfers so that the system will not spend all of 49 * its time context switching. PIPE_SIZE is constrained by the 50 * amount of kernel virtual memory. 51 */ 52 53 #include <sys/param.h> 54 #include <sys/systm.h> 55 #include <sys/proc.h> 56 #include <sys/fcntl.h> 57 #include <sys/file.h> 58 #include <sys/filedesc.h> 59 #include <sys/filio.h> 60 #include <sys/ttycom.h> 61 #include <sys/stat.h> 62 #include <sys/poll.h> 63 #include <sys/select.h> 64 #include <sys/signalvar.h> 65 #include <sys/sysproto.h> 66 #include <sys/pipe.h> 67 #include <sys/vnode.h> 68 #include <sys/uio.h> 69 #include <sys/event.h> 70 71 #include <vm/vm.h> 72 #include <vm/vm_param.h> 73 #include <sys/lock.h> 74 #include <vm/vm_object.h> 75 #include <vm/vm_kern.h> 76 #include <vm/vm_extern.h> 77 #include <vm/pmap.h> 78 #include <vm/vm_map.h> 79 #include <vm/vm_page.h> 80 #include <vm/vm_zone.h> 81 82 #include <sys/file2.h> 83 84 /* 85 * Use this define if you want to disable *fancy* VM things. Expect an 86 * approx 30% decrease in transfer rate. This could be useful for 87 * NetBSD or OpenBSD. 88 */ 89 /* #define PIPE_NODIRECT */ 90 91 /* 92 * interfaces to the outside world 93 */ 94 static int pipe_read __P((struct file *fp, struct uio *uio, 95 struct ucred *cred, int flags, struct thread *td)); 96 static int pipe_write __P((struct file *fp, struct uio *uio, 97 struct ucred *cred, int flags, struct thread *td)); 98 static int pipe_close __P((struct file *fp, struct thread *td)); 99 static int pipe_poll __P((struct file *fp, int events, struct ucred *cred, 100 struct thread *td)); 101 static int pipe_kqfilter __P((struct file *fp, struct knote *kn)); 102 static int pipe_stat __P((struct file *fp, struct stat *sb, struct thread *td)); 103 static int pipe_ioctl __P((struct file *fp, u_long cmd, caddr_t data, struct thread *td)); 104 105 static struct fileops pipeops = { 106 pipe_read, pipe_write, pipe_ioctl, pipe_poll, pipe_kqfilter, 107 pipe_stat, pipe_close 108 }; 109 110 static void filt_pipedetach(struct knote *kn); 111 static int filt_piperead(struct knote *kn, long hint); 112 static int filt_pipewrite(struct knote *kn, long hint); 113 114 static struct filterops pipe_rfiltops = 115 { 1, NULL, filt_pipedetach, filt_piperead }; 116 static struct filterops pipe_wfiltops = 117 { 1, NULL, filt_pipedetach, filt_pipewrite }; 118 119 120 /* 121 * Default pipe buffer size(s), this can be kind-of large now because pipe 122 * space is pageable. The pipe code will try to maintain locality of 123 * reference for performance reasons, so small amounts of outstanding I/O 124 * will not wipe the cache. 125 */ 126 #define MINPIPESIZE (PIPE_SIZE/3) 127 #define MAXPIPESIZE (2*PIPE_SIZE/3) 128 129 /* 130 * Maximum amount of kva for pipes -- this is kind-of a soft limit, but 131 * is there so that on large systems, we don't exhaust it. 132 */ 133 #define MAXPIPEKVA (8*1024*1024) 134 135 /* 136 * Limit for direct transfers, we cannot, of course limit 137 * the amount of kva for pipes in general though. 138 */ 139 #define LIMITPIPEKVA (16*1024*1024) 140 141 /* 142 * Limit the number of "big" pipes 143 */ 144 #define LIMITBIGPIPES 32 145 static int nbigpipe; 146 147 static int amountpipekva; 148 149 static void pipeclose __P((struct pipe *cpipe)); 150 static void pipe_free_kmem __P((struct pipe *cpipe)); 151 static int pipe_create __P((struct pipe **cpipep)); 152 static __inline int pipelock __P((struct pipe *cpipe, int catch)); 153 static __inline void pipeunlock __P((struct pipe *cpipe)); 154 static __inline void pipeselwakeup __P((struct pipe *cpipe)); 155 #ifndef PIPE_NODIRECT 156 static int pipe_build_write_buffer __P((struct pipe *wpipe, struct uio *uio)); 157 static void pipe_destroy_write_buffer __P((struct pipe *wpipe)); 158 static int pipe_direct_write __P((struct pipe *wpipe, struct uio *uio)); 159 static void pipe_clone_write_buffer __P((struct pipe *wpipe)); 160 #endif 161 static int pipespace __P((struct pipe *cpipe, int size)); 162 163 static vm_zone_t pipe_zone; 164 165 /* 166 * The pipe system call for the DTYPE_PIPE type of pipes 167 * 168 * pipe_ARgs(int dummy) 169 */ 170 171 /* ARGSUSED */ 172 int 173 pipe(struct pipe_args *uap) 174 { 175 struct thread *td = curthread; 176 struct proc *p = td->td_proc; 177 struct filedesc *fdp; 178 struct file *rf, *wf; 179 struct pipe *rpipe, *wpipe; 180 int fd1, fd2, error; 181 182 KKASSERT(p); 183 fdp = p->p_fd; 184 185 if (pipe_zone == NULL) 186 pipe_zone = zinit("PIPE", sizeof(struct pipe), 0, 0, 4); 187 188 rpipe = wpipe = NULL; 189 if (pipe_create(&rpipe) || pipe_create(&wpipe)) { 190 pipeclose(rpipe); 191 pipeclose(wpipe); 192 return (ENFILE); 193 } 194 195 rpipe->pipe_state |= PIPE_DIRECTOK; 196 wpipe->pipe_state |= PIPE_DIRECTOK; 197 198 error = falloc(p, &rf, &fd1); 199 if (error) { 200 pipeclose(rpipe); 201 pipeclose(wpipe); 202 return (error); 203 } 204 fhold(rf); 205 uap->lmsg.u.ms_fds[0] = fd1; 206 207 /* 208 * Warning: once we've gotten past allocation of the fd for the 209 * read-side, we can only drop the read side via fdrop() in order 210 * to avoid races against processes which manage to dup() the read 211 * side while we are blocked trying to allocate the write side. 212 */ 213 rf->f_flag = FREAD | FWRITE; 214 rf->f_type = DTYPE_PIPE; 215 rf->f_data = (caddr_t)rpipe; 216 rf->f_ops = &pipeops; 217 error = falloc(p, &wf, &fd2); 218 if (error) { 219 if (fdp->fd_ofiles[fd1] == rf) { 220 fdp->fd_ofiles[fd1] = NULL; 221 fdrop(rf, td); 222 } 223 fdrop(rf, td); 224 /* rpipe has been closed by fdrop(). */ 225 pipeclose(wpipe); 226 return (error); 227 } 228 wf->f_flag = FREAD | FWRITE; 229 wf->f_type = DTYPE_PIPE; 230 wf->f_data = (caddr_t)wpipe; 231 wf->f_ops = &pipeops; 232 uap->lmsg.u.ms_fds[1] = fd2; 233 234 rpipe->pipe_peer = wpipe; 235 wpipe->pipe_peer = rpipe; 236 fdrop(rf, td); 237 238 return (0); 239 } 240 241 /* 242 * Allocate kva for pipe circular buffer, the space is pageable 243 * This routine will 'realloc' the size of a pipe safely, if it fails 244 * it will retain the old buffer. 245 * If it fails it will return ENOMEM. 246 */ 247 static int 248 pipespace(cpipe, size) 249 struct pipe *cpipe; 250 int size; 251 { 252 struct vm_object *object; 253 caddr_t buffer; 254 int npages, error; 255 256 npages = round_page(size)/PAGE_SIZE; 257 /* 258 * Create an object, I don't like the idea of paging to/from 259 * kernel_object. 260 * XXX -- minor change needed here for NetBSD/OpenBSD VM systems. 261 */ 262 object = vm_object_allocate(OBJT_DEFAULT, npages); 263 buffer = (caddr_t) vm_map_min(kernel_map); 264 265 /* 266 * Insert the object into the kernel map, and allocate kva for it. 267 * The map entry is, by default, pageable. 268 * XXX -- minor change needed here for NetBSD/OpenBSD VM systems. 269 */ 270 error = vm_map_find(kernel_map, object, 0, 271 (vm_offset_t *) &buffer, size, 1, 272 VM_PROT_ALL, VM_PROT_ALL, 0); 273 274 if (error != KERN_SUCCESS) { 275 vm_object_deallocate(object); 276 return (ENOMEM); 277 } 278 279 /* free old resources if we're resizing */ 280 pipe_free_kmem(cpipe); 281 cpipe->pipe_buffer.object = object; 282 cpipe->pipe_buffer.buffer = buffer; 283 cpipe->pipe_buffer.size = size; 284 cpipe->pipe_buffer.in = 0; 285 cpipe->pipe_buffer.out = 0; 286 cpipe->pipe_buffer.cnt = 0; 287 amountpipekva += cpipe->pipe_buffer.size; 288 return (0); 289 } 290 291 /* 292 * initialize and allocate VM and memory for pipe 293 */ 294 static int 295 pipe_create(cpipep) 296 struct pipe **cpipep; 297 { 298 struct pipe *cpipe; 299 int error; 300 301 *cpipep = zalloc(pipe_zone); 302 if (*cpipep == NULL) 303 return (ENOMEM); 304 305 cpipe = *cpipep; 306 307 /* so pipespace()->pipe_free_kmem() doesn't follow junk pointer */ 308 cpipe->pipe_buffer.object = NULL; 309 #ifndef PIPE_NODIRECT 310 cpipe->pipe_map.kva = NULL; 311 #endif 312 /* 313 * protect so pipeclose() doesn't follow a junk pointer 314 * if pipespace() fails. 315 */ 316 bzero(&cpipe->pipe_sel, sizeof(cpipe->pipe_sel)); 317 cpipe->pipe_state = 0; 318 cpipe->pipe_peer = NULL; 319 cpipe->pipe_busy = 0; 320 321 #ifndef PIPE_NODIRECT 322 /* 323 * pipe data structure initializations to support direct pipe I/O 324 */ 325 cpipe->pipe_map.cnt = 0; 326 cpipe->pipe_map.kva = 0; 327 cpipe->pipe_map.pos = 0; 328 cpipe->pipe_map.npages = 0; 329 /* cpipe->pipe_map.ms[] = invalid */ 330 #endif 331 332 error = pipespace(cpipe, PIPE_SIZE); 333 if (error) 334 return (error); 335 336 vfs_timestamp(&cpipe->pipe_ctime); 337 cpipe->pipe_atime = cpipe->pipe_ctime; 338 cpipe->pipe_mtime = cpipe->pipe_ctime; 339 340 return (0); 341 } 342 343 344 /* 345 * lock a pipe for I/O, blocking other access 346 */ 347 static __inline int 348 pipelock(cpipe, catch) 349 struct pipe *cpipe; 350 int catch; 351 { 352 int error; 353 354 while (cpipe->pipe_state & PIPE_LOCK) { 355 cpipe->pipe_state |= PIPE_LWANT; 356 error = tsleep(cpipe, (catch ? PCATCH : 0), "pipelk", 0); 357 if (error != 0) 358 return (error); 359 } 360 cpipe->pipe_state |= PIPE_LOCK; 361 return (0); 362 } 363 364 /* 365 * unlock a pipe I/O lock 366 */ 367 static __inline void 368 pipeunlock(cpipe) 369 struct pipe *cpipe; 370 { 371 372 cpipe->pipe_state &= ~PIPE_LOCK; 373 if (cpipe->pipe_state & PIPE_LWANT) { 374 cpipe->pipe_state &= ~PIPE_LWANT; 375 wakeup(cpipe); 376 } 377 } 378 379 static __inline void 380 pipeselwakeup(cpipe) 381 struct pipe *cpipe; 382 { 383 384 if (cpipe->pipe_state & PIPE_SEL) { 385 cpipe->pipe_state &= ~PIPE_SEL; 386 selwakeup(&cpipe->pipe_sel); 387 } 388 if ((cpipe->pipe_state & PIPE_ASYNC) && cpipe->pipe_sigio) 389 pgsigio(cpipe->pipe_sigio, SIGIO, 0); 390 KNOTE(&cpipe->pipe_sel.si_note, 0); 391 } 392 393 /* ARGSUSED */ 394 static int 395 pipe_read(struct file *fp, struct uio *uio, struct ucred *cred, 396 int flags, struct thread *td) 397 { 398 struct pipe *rpipe = (struct pipe *) fp->f_data; 399 int error; 400 int nread = 0; 401 u_int size; 402 403 ++rpipe->pipe_busy; 404 error = pipelock(rpipe, 1); 405 if (error) 406 goto unlocked_error; 407 408 while (uio->uio_resid) { 409 /* 410 * normal pipe buffer receive 411 */ 412 if (rpipe->pipe_buffer.cnt > 0) { 413 size = rpipe->pipe_buffer.size - rpipe->pipe_buffer.out; 414 if (size > rpipe->pipe_buffer.cnt) 415 size = rpipe->pipe_buffer.cnt; 416 if (size > (u_int) uio->uio_resid) 417 size = (u_int) uio->uio_resid; 418 419 error = uiomove(&rpipe->pipe_buffer.buffer[rpipe->pipe_buffer.out], 420 size, uio); 421 if (error) 422 break; 423 424 rpipe->pipe_buffer.out += size; 425 if (rpipe->pipe_buffer.out >= rpipe->pipe_buffer.size) 426 rpipe->pipe_buffer.out = 0; 427 428 rpipe->pipe_buffer.cnt -= size; 429 430 /* 431 * If there is no more to read in the pipe, reset 432 * its pointers to the beginning. This improves 433 * cache hit stats. 434 */ 435 if (rpipe->pipe_buffer.cnt == 0) { 436 rpipe->pipe_buffer.in = 0; 437 rpipe->pipe_buffer.out = 0; 438 } 439 nread += size; 440 #ifndef PIPE_NODIRECT 441 /* 442 * Direct copy, bypassing a kernel buffer. 443 */ 444 } else if ((size = rpipe->pipe_map.cnt) && 445 (rpipe->pipe_state & PIPE_DIRECTW)) { 446 caddr_t va; 447 if (size > (u_int) uio->uio_resid) 448 size = (u_int) uio->uio_resid; 449 450 va = (caddr_t) rpipe->pipe_map.kva + 451 rpipe->pipe_map.pos; 452 error = uiomove(va, size, uio); 453 if (error) 454 break; 455 nread += size; 456 rpipe->pipe_map.pos += size; 457 rpipe->pipe_map.cnt -= size; 458 if (rpipe->pipe_map.cnt == 0) { 459 rpipe->pipe_state &= ~PIPE_DIRECTW; 460 wakeup(rpipe); 461 } 462 #endif 463 } else { 464 /* 465 * detect EOF condition 466 * read returns 0 on EOF, no need to set error 467 */ 468 if (rpipe->pipe_state & PIPE_EOF) 469 break; 470 471 /* 472 * If the "write-side" has been blocked, wake it up now. 473 */ 474 if (rpipe->pipe_state & PIPE_WANTW) { 475 rpipe->pipe_state &= ~PIPE_WANTW; 476 wakeup(rpipe); 477 } 478 479 /* 480 * Break if some data was read. 481 */ 482 if (nread > 0) 483 break; 484 485 /* 486 * Unlock the pipe buffer for our remaining processing. We 487 * will either break out with an error or we will sleep and 488 * relock to loop. 489 */ 490 pipeunlock(rpipe); 491 492 /* 493 * Handle non-blocking mode operation or 494 * wait for more data. 495 */ 496 if (fp->f_flag & FNONBLOCK) { 497 error = EAGAIN; 498 } else { 499 rpipe->pipe_state |= PIPE_WANTR; 500 if ((error = tsleep(rpipe, PCATCH, 501 "piperd", 0)) == 0) { 502 error = pipelock(rpipe, 1); 503 } 504 } 505 if (error) 506 goto unlocked_error; 507 } 508 } 509 pipeunlock(rpipe); 510 511 if (error == 0) 512 vfs_timestamp(&rpipe->pipe_atime); 513 unlocked_error: 514 --rpipe->pipe_busy; 515 516 /* 517 * PIPE_WANT processing only makes sense if pipe_busy is 0. 518 */ 519 if ((rpipe->pipe_busy == 0) && (rpipe->pipe_state & PIPE_WANT)) { 520 rpipe->pipe_state &= ~(PIPE_WANT|PIPE_WANTW); 521 wakeup(rpipe); 522 } else if (rpipe->pipe_buffer.cnt < MINPIPESIZE) { 523 /* 524 * Handle write blocking hysteresis. 525 */ 526 if (rpipe->pipe_state & PIPE_WANTW) { 527 rpipe->pipe_state &= ~PIPE_WANTW; 528 wakeup(rpipe); 529 } 530 } 531 532 if ((rpipe->pipe_buffer.size - rpipe->pipe_buffer.cnt) >= PIPE_BUF) 533 pipeselwakeup(rpipe); 534 535 return (error); 536 } 537 538 #ifndef PIPE_NODIRECT 539 /* 540 * Map the sending processes' buffer into kernel space and wire it. 541 * This is similar to a physical write operation. 542 */ 543 static int 544 pipe_build_write_buffer(wpipe, uio) 545 struct pipe *wpipe; 546 struct uio *uio; 547 { 548 u_int size; 549 int i; 550 vm_offset_t addr, endaddr, paddr; 551 552 size = (u_int) uio->uio_iov->iov_len; 553 if (size > wpipe->pipe_buffer.size) 554 size = wpipe->pipe_buffer.size; 555 556 endaddr = round_page((vm_offset_t)uio->uio_iov->iov_base + size); 557 addr = trunc_page((vm_offset_t)uio->uio_iov->iov_base); 558 for (i = 0; addr < endaddr; addr += PAGE_SIZE, i++) { 559 vm_page_t m; 560 561 if (vm_fault_quick((caddr_t)addr, VM_PROT_READ) < 0 || 562 (paddr = pmap_kextract(addr)) == 0) { 563 int j; 564 565 for (j = 0; j < i; j++) 566 vm_page_unwire(wpipe->pipe_map.ms[j], 1); 567 return (EFAULT); 568 } 569 570 m = PHYS_TO_VM_PAGE(paddr); 571 vm_page_wire(m); 572 wpipe->pipe_map.ms[i] = m; 573 } 574 575 /* 576 * set up the control block 577 */ 578 wpipe->pipe_map.npages = i; 579 wpipe->pipe_map.pos = 580 ((vm_offset_t) uio->uio_iov->iov_base) & PAGE_MASK; 581 wpipe->pipe_map.cnt = size; 582 583 /* 584 * and map the buffer 585 */ 586 if (wpipe->pipe_map.kva == 0) { 587 /* 588 * We need to allocate space for an extra page because the 589 * address range might (will) span pages at times. 590 */ 591 wpipe->pipe_map.kva = kmem_alloc_pageable(kernel_map, 592 wpipe->pipe_buffer.size + PAGE_SIZE); 593 amountpipekva += wpipe->pipe_buffer.size + PAGE_SIZE; 594 } 595 pmap_qenter(wpipe->pipe_map.kva, wpipe->pipe_map.ms, 596 wpipe->pipe_map.npages); 597 598 /* 599 * and update the uio data 600 */ 601 602 uio->uio_iov->iov_len -= size; 603 uio->uio_iov->iov_base += size; 604 if (uio->uio_iov->iov_len == 0) 605 uio->uio_iov++; 606 uio->uio_resid -= size; 607 uio->uio_offset += size; 608 return (0); 609 } 610 611 /* 612 * unmap and unwire the process buffer 613 */ 614 static void 615 pipe_destroy_write_buffer(wpipe) 616 struct pipe *wpipe; 617 { 618 int i; 619 620 if (wpipe->pipe_map.kva) { 621 pmap_qremove(wpipe->pipe_map.kva, wpipe->pipe_map.npages); 622 623 if (amountpipekva > MAXPIPEKVA) { 624 vm_offset_t kva = wpipe->pipe_map.kva; 625 wpipe->pipe_map.kva = 0; 626 kmem_free(kernel_map, kva, 627 wpipe->pipe_buffer.size + PAGE_SIZE); 628 amountpipekva -= wpipe->pipe_buffer.size + PAGE_SIZE; 629 } 630 } 631 for (i = 0; i < wpipe->pipe_map.npages; i++) 632 vm_page_unwire(wpipe->pipe_map.ms[i], 1); 633 wpipe->pipe_map.npages = 0; 634 } 635 636 /* 637 * In the case of a signal, the writing process might go away. This 638 * code copies the data into the circular buffer so that the source 639 * pages can be freed without loss of data. 640 */ 641 static void 642 pipe_clone_write_buffer(wpipe) 643 struct pipe *wpipe; 644 { 645 int size; 646 int pos; 647 648 size = wpipe->pipe_map.cnt; 649 pos = wpipe->pipe_map.pos; 650 bcopy((caddr_t) wpipe->pipe_map.kva + pos, 651 (caddr_t) wpipe->pipe_buffer.buffer, size); 652 653 wpipe->pipe_buffer.in = size; 654 wpipe->pipe_buffer.out = 0; 655 wpipe->pipe_buffer.cnt = size; 656 wpipe->pipe_state &= ~PIPE_DIRECTW; 657 658 pipe_destroy_write_buffer(wpipe); 659 } 660 661 /* 662 * This implements the pipe buffer write mechanism. Note that only 663 * a direct write OR a normal pipe write can be pending at any given time. 664 * If there are any characters in the pipe buffer, the direct write will 665 * be deferred until the receiving process grabs all of the bytes from 666 * the pipe buffer. Then the direct mapping write is set-up. 667 */ 668 static int 669 pipe_direct_write(wpipe, uio) 670 struct pipe *wpipe; 671 struct uio *uio; 672 { 673 int error; 674 675 retry: 676 while (wpipe->pipe_state & PIPE_DIRECTW) { 677 if (wpipe->pipe_state & PIPE_WANTR) { 678 wpipe->pipe_state &= ~PIPE_WANTR; 679 wakeup(wpipe); 680 } 681 wpipe->pipe_state |= PIPE_WANTW; 682 error = tsleep(wpipe, PCATCH, "pipdww", 0); 683 if (error) 684 goto error1; 685 if (wpipe->pipe_state & PIPE_EOF) { 686 error = EPIPE; 687 goto error1; 688 } 689 } 690 wpipe->pipe_map.cnt = 0; /* transfer not ready yet */ 691 if (wpipe->pipe_buffer.cnt > 0) { 692 if (wpipe->pipe_state & PIPE_WANTR) { 693 wpipe->pipe_state &= ~PIPE_WANTR; 694 wakeup(wpipe); 695 } 696 697 wpipe->pipe_state |= PIPE_WANTW; 698 error = tsleep(wpipe, PCATCH, "pipdwc", 0); 699 if (error) 700 goto error1; 701 if (wpipe->pipe_state & PIPE_EOF) { 702 error = EPIPE; 703 goto error1; 704 } 705 goto retry; 706 } 707 708 wpipe->pipe_state |= PIPE_DIRECTW; 709 710 error = pipe_build_write_buffer(wpipe, uio); 711 if (error) { 712 wpipe->pipe_state &= ~PIPE_DIRECTW; 713 goto error1; 714 } 715 716 error = 0; 717 while (!error && (wpipe->pipe_state & PIPE_DIRECTW)) { 718 if (wpipe->pipe_state & PIPE_EOF) { 719 pipelock(wpipe, 0); 720 pipe_destroy_write_buffer(wpipe); 721 pipeunlock(wpipe); 722 pipeselwakeup(wpipe); 723 error = EPIPE; 724 goto error1; 725 } 726 if (wpipe->pipe_state & PIPE_WANTR) { 727 wpipe->pipe_state &= ~PIPE_WANTR; 728 wakeup(wpipe); 729 } 730 pipeselwakeup(wpipe); 731 error = tsleep(wpipe, PCATCH, "pipdwt", 0); 732 } 733 734 pipelock(wpipe,0); 735 if (wpipe->pipe_state & PIPE_DIRECTW) { 736 /* 737 * this bit of trickery substitutes a kernel buffer for 738 * the process that might be going away. 739 */ 740 pipe_clone_write_buffer(wpipe); 741 } else { 742 pipe_destroy_write_buffer(wpipe); 743 } 744 pipeunlock(wpipe); 745 return (error); 746 747 error1: 748 wakeup(wpipe); 749 return (error); 750 } 751 #endif 752 753 static int 754 pipe_write(struct file *fp, struct uio *uio, struct ucred *cred, 755 int flags, struct thread *td) 756 { 757 int error = 0; 758 int orig_resid; 759 struct pipe *wpipe, *rpipe; 760 761 rpipe = (struct pipe *) fp->f_data; 762 wpipe = rpipe->pipe_peer; 763 764 /* 765 * detect loss of pipe read side, issue SIGPIPE if lost. 766 */ 767 if ((wpipe == NULL) || (wpipe->pipe_state & PIPE_EOF)) { 768 return (EPIPE); 769 } 770 ++wpipe->pipe_busy; 771 772 /* 773 * If it is advantageous to resize the pipe buffer, do 774 * so. 775 */ 776 if ((uio->uio_resid > PIPE_SIZE) && 777 (nbigpipe < LIMITBIGPIPES) && 778 (wpipe->pipe_state & PIPE_DIRECTW) == 0 && 779 (wpipe->pipe_buffer.size <= PIPE_SIZE) && 780 (wpipe->pipe_buffer.cnt == 0)) { 781 782 if ((error = pipelock(wpipe,1)) == 0) { 783 if (pipespace(wpipe, BIG_PIPE_SIZE) == 0) 784 nbigpipe++; 785 pipeunlock(wpipe); 786 } 787 } 788 789 /* 790 * If an early error occured unbusy and return, waking up any pending 791 * readers. 792 */ 793 if (error) { 794 --wpipe->pipe_busy; 795 if ((wpipe->pipe_busy == 0) && 796 (wpipe->pipe_state & PIPE_WANT)) { 797 wpipe->pipe_state &= ~(PIPE_WANT | PIPE_WANTR); 798 wakeup(wpipe); 799 } 800 return(error); 801 } 802 803 KASSERT(wpipe->pipe_buffer.buffer != NULL, ("pipe buffer gone")); 804 805 orig_resid = uio->uio_resid; 806 807 while (uio->uio_resid) { 808 int space; 809 810 #ifndef PIPE_NODIRECT 811 /* 812 * If the transfer is large, we can gain performance if 813 * we do process-to-process copies directly. 814 * If the write is non-blocking, we don't use the 815 * direct write mechanism. 816 * 817 * The direct write mechanism will detect the reader going 818 * away on us. 819 */ 820 if ((uio->uio_iov->iov_len >= PIPE_MINDIRECT) && 821 (fp->f_flag & FNONBLOCK) == 0 && 822 (wpipe->pipe_map.kva || (amountpipekva < LIMITPIPEKVA)) && 823 (uio->uio_iov->iov_len >= PIPE_MINDIRECT)) { 824 error = pipe_direct_write( wpipe, uio); 825 if (error) 826 break; 827 continue; 828 } 829 #endif 830 831 /* 832 * Pipe buffered writes cannot be coincidental with 833 * direct writes. We wait until the currently executing 834 * direct write is completed before we start filling the 835 * pipe buffer. We break out if a signal occurs or the 836 * reader goes away. 837 */ 838 retrywrite: 839 while (wpipe->pipe_state & PIPE_DIRECTW) { 840 if (wpipe->pipe_state & PIPE_WANTR) { 841 wpipe->pipe_state &= ~PIPE_WANTR; 842 wakeup(wpipe); 843 } 844 error = tsleep(wpipe, PCATCH, "pipbww", 0); 845 if (wpipe->pipe_state & PIPE_EOF) 846 break; 847 if (error) 848 break; 849 } 850 if (wpipe->pipe_state & PIPE_EOF) { 851 error = EPIPE; 852 break; 853 } 854 855 space = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt; 856 857 /* Writes of size <= PIPE_BUF must be atomic. */ 858 if ((space < uio->uio_resid) && (orig_resid <= PIPE_BUF)) 859 space = 0; 860 861 if (space > 0 && (wpipe->pipe_buffer.cnt < PIPE_SIZE)) { 862 if ((error = pipelock(wpipe,1)) == 0) { 863 int size; /* Transfer size */ 864 int segsize; /* first segment to transfer */ 865 866 /* 867 * It is possible for a direct write to 868 * slip in on us... handle it here... 869 */ 870 if (wpipe->pipe_state & PIPE_DIRECTW) { 871 pipeunlock(wpipe); 872 goto retrywrite; 873 } 874 /* 875 * If a process blocked in uiomove, our 876 * value for space might be bad. 877 * 878 * XXX will we be ok if the reader has gone 879 * away here? 880 */ 881 if (space > wpipe->pipe_buffer.size - 882 wpipe->pipe_buffer.cnt) { 883 pipeunlock(wpipe); 884 goto retrywrite; 885 } 886 887 /* 888 * Transfer size is minimum of uio transfer 889 * and free space in pipe buffer. 890 */ 891 if (space > uio->uio_resid) 892 size = uio->uio_resid; 893 else 894 size = space; 895 /* 896 * First segment to transfer is minimum of 897 * transfer size and contiguous space in 898 * pipe buffer. If first segment to transfer 899 * is less than the transfer size, we've got 900 * a wraparound in the buffer. 901 */ 902 segsize = wpipe->pipe_buffer.size - 903 wpipe->pipe_buffer.in; 904 if (segsize > size) 905 segsize = size; 906 907 /* Transfer first segment */ 908 909 error = uiomove(&wpipe->pipe_buffer.buffer[wpipe->pipe_buffer.in], 910 segsize, uio); 911 912 if (error == 0 && segsize < size) { 913 /* 914 * Transfer remaining part now, to 915 * support atomic writes. Wraparound 916 * happened. 917 */ 918 if (wpipe->pipe_buffer.in + segsize != 919 wpipe->pipe_buffer.size) 920 panic("Expected pipe buffer wraparound disappeared"); 921 922 error = uiomove(&wpipe->pipe_buffer.buffer[0], 923 size - segsize, uio); 924 } 925 if (error == 0) { 926 wpipe->pipe_buffer.in += size; 927 if (wpipe->pipe_buffer.in >= 928 wpipe->pipe_buffer.size) { 929 if (wpipe->pipe_buffer.in != size - segsize + wpipe->pipe_buffer.size) 930 panic("Expected wraparound bad"); 931 wpipe->pipe_buffer.in = size - segsize; 932 } 933 934 wpipe->pipe_buffer.cnt += size; 935 if (wpipe->pipe_buffer.cnt > wpipe->pipe_buffer.size) 936 panic("Pipe buffer overflow"); 937 938 } 939 pipeunlock(wpipe); 940 } 941 if (error) 942 break; 943 944 } else { 945 /* 946 * If the "read-side" has been blocked, wake it up now. 947 */ 948 if (wpipe->pipe_state & PIPE_WANTR) { 949 wpipe->pipe_state &= ~PIPE_WANTR; 950 wakeup(wpipe); 951 } 952 953 /* 954 * don't block on non-blocking I/O 955 */ 956 if (fp->f_flag & FNONBLOCK) { 957 error = EAGAIN; 958 break; 959 } 960 961 /* 962 * We have no more space and have something to offer, 963 * wake up select/poll. 964 */ 965 pipeselwakeup(wpipe); 966 967 wpipe->pipe_state |= PIPE_WANTW; 968 error = tsleep(wpipe, PCATCH, "pipewr", 0); 969 if (error != 0) 970 break; 971 /* 972 * If read side wants to go away, we just issue a signal 973 * to ourselves. 974 */ 975 if (wpipe->pipe_state & PIPE_EOF) { 976 error = EPIPE; 977 break; 978 } 979 } 980 } 981 982 --wpipe->pipe_busy; 983 984 if ((wpipe->pipe_busy == 0) && (wpipe->pipe_state & PIPE_WANT)) { 985 wpipe->pipe_state &= ~(PIPE_WANT | PIPE_WANTR); 986 wakeup(wpipe); 987 } else if (wpipe->pipe_buffer.cnt > 0) { 988 /* 989 * If we have put any characters in the buffer, we wake up 990 * the reader. 991 */ 992 if (wpipe->pipe_state & PIPE_WANTR) { 993 wpipe->pipe_state &= ~PIPE_WANTR; 994 wakeup(wpipe); 995 } 996 } 997 998 /* 999 * Don't return EPIPE if I/O was successful 1000 */ 1001 if ((wpipe->pipe_buffer.cnt == 0) && 1002 (uio->uio_resid == 0) && 1003 (error == EPIPE)) { 1004 error = 0; 1005 } 1006 1007 if (error == 0) 1008 vfs_timestamp(&wpipe->pipe_mtime); 1009 1010 /* 1011 * We have something to offer, 1012 * wake up select/poll. 1013 */ 1014 if (wpipe->pipe_buffer.cnt) 1015 pipeselwakeup(wpipe); 1016 1017 return (error); 1018 } 1019 1020 /* 1021 * we implement a very minimal set of ioctls for compatibility with sockets. 1022 */ 1023 int 1024 pipe_ioctl(struct file *fp, u_long cmd, caddr_t data, struct thread *td) 1025 { 1026 struct pipe *mpipe = (struct pipe *)fp->f_data; 1027 1028 switch (cmd) { 1029 1030 case FIONBIO: 1031 return (0); 1032 1033 case FIOASYNC: 1034 if (*(int *)data) { 1035 mpipe->pipe_state |= PIPE_ASYNC; 1036 } else { 1037 mpipe->pipe_state &= ~PIPE_ASYNC; 1038 } 1039 return (0); 1040 1041 case FIONREAD: 1042 if (mpipe->pipe_state & PIPE_DIRECTW) 1043 *(int *)data = mpipe->pipe_map.cnt; 1044 else 1045 *(int *)data = mpipe->pipe_buffer.cnt; 1046 return (0); 1047 1048 case FIOSETOWN: 1049 return (fsetown(*(int *)data, &mpipe->pipe_sigio)); 1050 1051 case FIOGETOWN: 1052 *(int *)data = fgetown(mpipe->pipe_sigio); 1053 return (0); 1054 1055 /* This is deprecated, FIOSETOWN should be used instead. */ 1056 case TIOCSPGRP: 1057 return (fsetown(-(*(int *)data), &mpipe->pipe_sigio)); 1058 1059 /* This is deprecated, FIOGETOWN should be used instead. */ 1060 case TIOCGPGRP: 1061 *(int *)data = -fgetown(mpipe->pipe_sigio); 1062 return (0); 1063 1064 } 1065 return (ENOTTY); 1066 } 1067 1068 int 1069 pipe_poll(struct file *fp, int events, struct ucred *cred, struct thread *td) 1070 { 1071 struct pipe *rpipe = (struct pipe *)fp->f_data; 1072 struct pipe *wpipe; 1073 int revents = 0; 1074 1075 wpipe = rpipe->pipe_peer; 1076 if (events & (POLLIN | POLLRDNORM)) 1077 if ((rpipe->pipe_state & PIPE_DIRECTW) || 1078 (rpipe->pipe_buffer.cnt > 0) || 1079 (rpipe->pipe_state & PIPE_EOF)) 1080 revents |= events & (POLLIN | POLLRDNORM); 1081 1082 if (events & (POLLOUT | POLLWRNORM)) 1083 if (wpipe == NULL || (wpipe->pipe_state & PIPE_EOF) || 1084 (((wpipe->pipe_state & PIPE_DIRECTW) == 0) && 1085 (wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) >= PIPE_BUF)) 1086 revents |= events & (POLLOUT | POLLWRNORM); 1087 1088 if ((rpipe->pipe_state & PIPE_EOF) || 1089 (wpipe == NULL) || 1090 (wpipe->pipe_state & PIPE_EOF)) 1091 revents |= POLLHUP; 1092 1093 if (revents == 0) { 1094 if (events & (POLLIN | POLLRDNORM)) { 1095 selrecord(td, &rpipe->pipe_sel); 1096 rpipe->pipe_state |= PIPE_SEL; 1097 } 1098 1099 if (events & (POLLOUT | POLLWRNORM)) { 1100 selrecord(td, &wpipe->pipe_sel); 1101 wpipe->pipe_state |= PIPE_SEL; 1102 } 1103 } 1104 1105 return (revents); 1106 } 1107 1108 static int 1109 pipe_stat(struct file *fp, struct stat *ub, struct thread *td) 1110 { 1111 struct pipe *pipe = (struct pipe *)fp->f_data; 1112 1113 bzero((caddr_t)ub, sizeof(*ub)); 1114 ub->st_mode = S_IFIFO; 1115 ub->st_blksize = pipe->pipe_buffer.size; 1116 ub->st_size = pipe->pipe_buffer.cnt; 1117 ub->st_blocks = (ub->st_size + ub->st_blksize - 1) / ub->st_blksize; 1118 ub->st_atimespec = pipe->pipe_atime; 1119 ub->st_mtimespec = pipe->pipe_mtime; 1120 ub->st_ctimespec = pipe->pipe_ctime; 1121 /* 1122 * Left as 0: st_dev, st_ino, st_nlink, st_uid, st_gid, st_rdev, 1123 * st_flags, st_gen. 1124 * XXX (st_dev, st_ino) should be unique. 1125 */ 1126 return (0); 1127 } 1128 1129 /* ARGSUSED */ 1130 static int 1131 pipe_close(struct file *fp, struct thread *td) 1132 { 1133 struct pipe *cpipe = (struct pipe *)fp->f_data; 1134 1135 fp->f_ops = &badfileops; 1136 fp->f_data = NULL; 1137 funsetown(cpipe->pipe_sigio); 1138 pipeclose(cpipe); 1139 return (0); 1140 } 1141 1142 static void 1143 pipe_free_kmem(struct pipe *cpipe) 1144 { 1145 1146 if (cpipe->pipe_buffer.buffer != NULL) { 1147 if (cpipe->pipe_buffer.size > PIPE_SIZE) 1148 --nbigpipe; 1149 amountpipekva -= cpipe->pipe_buffer.size; 1150 kmem_free(kernel_map, 1151 (vm_offset_t)cpipe->pipe_buffer.buffer, 1152 cpipe->pipe_buffer.size); 1153 cpipe->pipe_buffer.buffer = NULL; 1154 } 1155 #ifndef PIPE_NODIRECT 1156 if (cpipe->pipe_map.kva != NULL) { 1157 amountpipekva -= cpipe->pipe_buffer.size + PAGE_SIZE; 1158 kmem_free(kernel_map, 1159 cpipe->pipe_map.kva, 1160 cpipe->pipe_buffer.size + PAGE_SIZE); 1161 cpipe->pipe_map.cnt = 0; 1162 cpipe->pipe_map.kva = 0; 1163 cpipe->pipe_map.pos = 0; 1164 cpipe->pipe_map.npages = 0; 1165 } 1166 #endif 1167 } 1168 1169 /* 1170 * shutdown the pipe 1171 */ 1172 static void 1173 pipeclose(struct pipe *cpipe) 1174 { 1175 struct pipe *ppipe; 1176 1177 if (cpipe) { 1178 1179 pipeselwakeup(cpipe); 1180 1181 /* 1182 * If the other side is blocked, wake it up saying that 1183 * we want to close it down. 1184 */ 1185 while (cpipe->pipe_busy) { 1186 wakeup(cpipe); 1187 cpipe->pipe_state |= PIPE_WANT | PIPE_EOF; 1188 tsleep(cpipe, 0, "pipecl", 0); 1189 } 1190 1191 /* 1192 * Disconnect from peer 1193 */ 1194 if ((ppipe = cpipe->pipe_peer) != NULL) { 1195 pipeselwakeup(ppipe); 1196 1197 ppipe->pipe_state |= PIPE_EOF; 1198 wakeup(ppipe); 1199 KNOTE(&ppipe->pipe_sel.si_note, 0); 1200 ppipe->pipe_peer = NULL; 1201 } 1202 /* 1203 * free resources 1204 */ 1205 pipe_free_kmem(cpipe); 1206 zfree(pipe_zone, cpipe); 1207 } 1208 } 1209 1210 /*ARGSUSED*/ 1211 static int 1212 pipe_kqfilter(struct file *fp, struct knote *kn) 1213 { 1214 struct pipe *cpipe = (struct pipe *)kn->kn_fp->f_data; 1215 1216 switch (kn->kn_filter) { 1217 case EVFILT_READ: 1218 kn->kn_fop = &pipe_rfiltops; 1219 break; 1220 case EVFILT_WRITE: 1221 kn->kn_fop = &pipe_wfiltops; 1222 cpipe = cpipe->pipe_peer; 1223 if (cpipe == NULL) 1224 /* other end of pipe has been closed */ 1225 return (EBADF); 1226 break; 1227 default: 1228 return (1); 1229 } 1230 kn->kn_hook = (caddr_t)cpipe; 1231 1232 SLIST_INSERT_HEAD(&cpipe->pipe_sel.si_note, kn, kn_selnext); 1233 return (0); 1234 } 1235 1236 static void 1237 filt_pipedetach(struct knote *kn) 1238 { 1239 struct pipe *cpipe = (struct pipe *)kn->kn_hook; 1240 1241 SLIST_REMOVE(&cpipe->pipe_sel.si_note, kn, knote, kn_selnext); 1242 } 1243 1244 /*ARGSUSED*/ 1245 static int 1246 filt_piperead(struct knote *kn, long hint) 1247 { 1248 struct pipe *rpipe = (struct pipe *)kn->kn_fp->f_data; 1249 struct pipe *wpipe = rpipe->pipe_peer; 1250 1251 kn->kn_data = rpipe->pipe_buffer.cnt; 1252 if ((kn->kn_data == 0) && (rpipe->pipe_state & PIPE_DIRECTW)) 1253 kn->kn_data = rpipe->pipe_map.cnt; 1254 1255 if ((rpipe->pipe_state & PIPE_EOF) || 1256 (wpipe == NULL) || (wpipe->pipe_state & PIPE_EOF)) { 1257 kn->kn_flags |= EV_EOF; 1258 return (1); 1259 } 1260 return (kn->kn_data > 0); 1261 } 1262 1263 /*ARGSUSED*/ 1264 static int 1265 filt_pipewrite(struct knote *kn, long hint) 1266 { 1267 struct pipe *rpipe = (struct pipe *)kn->kn_fp->f_data; 1268 struct pipe *wpipe = rpipe->pipe_peer; 1269 1270 if ((wpipe == NULL) || (wpipe->pipe_state & PIPE_EOF)) { 1271 kn->kn_data = 0; 1272 kn->kn_flags |= EV_EOF; 1273 return (1); 1274 } 1275 kn->kn_data = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt; 1276 if (wpipe->pipe_state & PIPE_DIRECTW) 1277 kn->kn_data = 0; 1278 1279 return (kn->kn_data >= PIPE_BUF); 1280 } 1281